Chrysler Repair: Engine Malfunction Indicator Light on, what to do?, malfunction indicator light, dodge dealer

Question
I have a 2002 Dodge Dakota and the malfunction indicator light went on (not blinking, but solid light).  Per advice from a Dodge Dealer (friend), disconnect the battery for 15 minutes and reconnect (sort of a restart of the system).  Light not on for about a week or so.  Light came back on.  Changed gas cap, disconnected battery (restart), and light was gone for a couple of weeks.  Light would appear briefly (like all other indicator lights) upon ignition which is as it should be.  

Light came back on, for a while.  Sometimes, the light is not on and also does not even appear at ignition.  This is the current status.

What could be wrong.  

Answer
Hi Ellen,
The light coming on while you are driving means that a problem with the engine control (or perhaps the transmission) has been detected which if unrepaired would increase air pollution, coded it with a number and stored the number in the memory of the controllers. If you disconnect the battery it erases the code so I would not do that anymore because it just delays finding out what is wrong.
The best thing to do is go to an Autozone Parts store if there is one near you and ask for help with a free readout of the fault code(s) that are currently stored. Find out the 4-digit number of the code and the name of the code and ask what they suggest might be the solution. Alternatively you can go to a repair shop that has advertised a "special" on code readout for around $40. If you find the problem to be a modest cost item then I would fix it. If not, then write back with the code and we'll talk about the possible approach to fixing the situation.
Roland